<?php
/**
 * Smarty plugin
 *
 * This plugin is only for Smarty2 BC
 * @package Smarty
 * @subpackage PluginsFunction
 */

/**
 * Smarty {math} function plugin
 *
 * Type:     function<br>
 * Name:     math<br>
 * Purpose:  handle math computations in template<br>
 * @link http://smarty.php.net/manual/en/language.function.math.php {math}
 * (Smarty online manual)
 * @author   Monte Ohrt <monte at ohrt dot com>
 * @param array $params parameters
 * @param object $template template object
 * @return string|null
 */
function smarty_function_math($params, $template) {
	// be sure equation parameter is present
	if (empty ( $params ['equation'] )) {
		trigger_error ( "math: missing equation parameter", E_USER_WARNING );
		return;
	}
	
	$equation = $params ['equation'];
	
	// make sure parenthesis are balanced
	if (substr_count ( $equation, "(" ) != substr_count ( $equation, ")" )) {
		trigger_error ( "math: unbalanced parenthesis", E_USER_WARNING );
		return;
	}
	
	// match all vars in equation, make sure all are passed
	preg_match_all ( "!(?:0x[a-fA-F0-9]+)|([a-zA-Z][a-zA-Z0-9_]*)!", $equation, $match );
	$allowed_funcs = array ('int', 'abs', 'ceil', 'cos', 'exp', 'floor', 'log', 'log10', 'max', 'min', 'pi', 'pow', 'rand', 'round', 'sin', 'sqrt', 'srand', 'tan' );
	
	foreach ( $match [1] as $curr_var ) {
		if ($curr_var && ! in_array ( $curr_var, array_keys ( $params ) ) && ! in_array ( $curr_var, $allowed_funcs )) {
			trigger_error ( "math: function call $curr_var not allowed", E_USER_WARNING );
			return;
		}
	}
	
	foreach ( $params as $key => $val ) {
		if ($key != "equation" && $key != "format" && $key != "assign") {
			// make sure value is not empty
			if (strlen ( $val ) == 0) {
				trigger_error ( "math: parameter $key is empty", E_USER_WARNING );
				return;
			}
			if (! is_numeric ( $val )) {
				trigger_error ( "math: parameter $key: is not numeric", E_USER_WARNING );
				return;
			}
			$equation = preg_replace ( "/\b$key\b/", " \$params['$key'] ", $equation );
		}
	}
	$smarty_math_result = null;
	eval ( "\$smarty_math_result = " . $equation . ";" );
	
	if (empty ( $params ['format'] )) {
		if (empty ( $params ['assign'] )) {
			return $smarty_math_result;
		} else {
			$template->assign ( $params ['assign'], $smarty_math_result );
		}
	} else {
		if (empty ( $params ['assign'] )) {
			printf ( $params ['format'], $smarty_math_result );
		} else {
			$template->assign ( $params ['assign'], sprintf ( $params ['format'], $smarty_math_result ) );
		}
	}
}

?>